Patent GB-613110-A (GB)
Title: Improvements in or relating to azo dyestuffs
IPC: C09B29/08
Filed: 1945-04-17
Abstract: 2-Methoxy-, 2-chloro- and 2-methyl-5-nitro-1 : 4-phenylenediamine are obtainable from 2-amino-5-nitroanisole, 2-amino-5-nitro-1-chlorobenzene and 2-amino-5-nitroluene respectively by reduction, acetylation, nitration and hydrolysis.  The Specification as open to inspection under Sect. 91 comprises also a reference to the preparation of 3 - nitro - 4 - N : N - dimethyl - p - phenylenediamino from 4 - dimethylamino - 1 - acetanilide by nitration with sodium nitrite and glacial acetic acid and hydrolysis with dilute hydrochloric acid.  This subject-matter does not appear in the Specification as accepted.ALSO:Artificial fibres of cellulose esters or ethers or other plastic material such as polyvinyl resins or superpolyamides are dyed in yellow to red and reddish brown shades by the application thereto of azo dyestuffs of the general formula <FORM:0613110/IV (c)/1> (wherein X represents a hydrogen or halogen atom or an alkyl or alkoxy radical, and R1 and R2 represent alkyl or hydroxyalkyl radicals, whilst the benzene ring on the right-hand side may contain further substituents, especially halogen atoms or alkyl, alkoxy or acylanimo radicals), if desired with subsequent diazotization on the fibre and development (e.g. with phenols, polyphenols, naphthols, pyrazolones or aromatic amines) to violet, blue, black, greenish black, olive and brown shades.  In an example, cellulose acetate rayon yarn is dyed from a bath in which the dyestuff 2-chloro - 5 - nitro - 1 : 4 - phenylenediamine --> N : N-d-(hydroxyethyl)-aniline is dispersed with the aid of yellow soap, and the dyeing is diazotized and developed with 2 : 3-hydroxynaphthoic acid, yielding a red-brown shade.  Azo dyestuffs of the general formula given above are manufactured by monodiazotizing a base of the general formula <FORM:0613110/IV (c)/2> and coupling with an amine of the general formula Phenyl-NR1R2 (wherein the phenyl group may carry further substituents provided that the p-position to the substituted amino group is free). Examples describe the preparation of the following dyestuffs: (1) nitro-p-phenylenediamine --> N : N - di - (hydroxyethyl) - aniline; (2) 2 - methoxy - 5 - nitro-1 : 4 - phenylenediamine --> N : N - di-hydroxyethyl) - aniline or N - methyl - N-hydroxyethylaniline; (3) 2-chloro-5-nitro-1 : 4-phenylenediamine --> the same coupling components.  Samples have been furnished under Sect. 2 (5) of the following dyestuffs (and of cellulose acetate fibres dyed therewith by the method of the example above): (A) 2-chloro-5-nitro-1 : 4-phenylenediamine --> 3-chloro - N : N - di-(hydroxyethyl) - aniline; (B) nitro-p-phenylenediamine --> 3 - acetylamino - N : N - (hydroxyethyl) - aniline; (C) 2 - methyl - 5 - nitro - 1 : 4-phenylenediamine --> N : N - di - (hydroxyethyl) - aniline; (D) nitro - p - phenylenediamine --> 3 - methyl - N : N - di - (hydroxyethyl) - aniline; (E) 2 - chloro - 5 - nitro - 1 : 4-phenylenediamine --> 5 - methyl - 2 - methoxy N : N-di-(hydroxyethyl)-aniline.  The Specification as open to inspection under Sect. 91 comprises also the manufacture and use of other dyestuffs of the general formula <FORM:0613110/IV (c)/3> wherein each X may represent hydrogen or halogen or an alkyl, alkoxy or similar group.  Aryl represents an aromatic radical which may carry substituents such as halogen atoms or alkyl, alkoxy, acylamino or similar groups, and R1, R2, R3 and R4 may represent hydrogen atoms or alkyl, aryl, aralkyl or cycloalkyl groups, optionally carrying substituents such as hydroxy, alkoxy or acyloxy groups, or R3 may be joined to Aryl to form a heterocyclic ring, but at least one of the pairs R1, R2 or R3, R4 must represent two hydrogen atoms.  Some of these dyestuffs may be made by the following alternative processes: (a) diazotization of an amine of the formula <FORM:0613110/IV (c)/4> and coupling with an amine Aryl NR3R4, followed by hydrolysis of the acylamino group; (b) diazotization of an amine of the formula <FORM:0613110/IV (c)/5> (wherein R1 and R2 do not represent hydrogen) and coupling with an amine Aryl NR3R4.  Additional examples describe the production of the following dyestuffs: nitro-p-phenylenediamine --> a  - naphthylamine; 2 - methoxy5-nitro - 1 : 4 - phenylenediamine --> amino-hydroquinone diethyl ether; 2-methyl-5-nitro-1 : 4 - phenylenediamine --> p - cresidine or a  - naphthylamine; 2 - nitro - 4 - N - acetyl - p-phenylenediamine --> a  - naphthylamine or N : N - di - (hydroxyethyl) - aniline, with subsequent hydrolysis; 3 - nitro - 4 - N : N - di-methyl - p - phenylenediamine --> p - cresidine or a -naphthylamine.  This subject-matter does not appear in the Specification as accepted.